The 2012 United States Senate elections, to be held November 6, 2012, include Republican, Democrat and Independent candidates vying for six-year terms and a seat in the 113th Congress. Democrats need to defend 21 seats and Republicans need only to defend 10 seats. Two seats held by Independents are up for election and lean Democrat: Bernie Sanders seeks re-election and Joe Lieberman is retiring.

Democrats' majority status and Harry Reid's Senate leadership are at stake. Some Democrats are growing uncomfortable as they decline to endorse Obama's shift on gay marriage. Of the 33 Democrats who have won their primaries, only 20 have clearly stated their support for gay marriage while 8 have stated their opposition. "Senate Majority Leader Harry Reid predicted Thursday the Democratic Party would adopt a pro-gay marriage plank in its platform." [1]

Tea Party-backed Republican Richard Mourdock will face Democrat Joe Donnelly after defeating 35-year incumbent Republican Richard Lugar in the Republican primary. The latest Rasmussen poll from August 1 has Mourdock up by 2 points at 42% to 40%.

* Nevada

Republican Dean Heller was appointed in 2011 to replace John Ensign and is considered the incumbent. He faces Rep. Shelley Berkley who cruised to victory in the Democratic primary. The latest Rasmussen poll from September 18 has Heller up by 1 point at 42% to 41%.

Toss Up

* Florida

Democrat Bill Nelson is the incumbent. He will face Republican Representative Connie Mack. Polls show Nelson below the 50 percent mark, which is bad news for an incumbent and Nelson cannot win if Romney takes Florida, a must-win state for him. As of September 2012, Nelson leads Mack by about 8 percentage points, depending on the poll.[1]

* Missouri

Democrat Claire McCaskill is the incumbent and faces movement conservativeTodd Akin, the Republican nominee. Since Akin's comments regarding pregnancy and "legitimate rape," Akin went from leading McCaskill by 6 points in prior polls to trailing her by 10 points in a Rasmussen Poll from August 22. The gap had lessened for Akin to 6 points in a September 12th poll, but grew again to an 8 point difference favoring McCaskill by an October 17th Rasmussen poll.[2] Now that Missouri has become what is likely to be a necessary win for Republicans to gain control of the Senate, and now that Akin can no longer drop from the race and be replaced by a different Republican on the ballot, he has received the support of a number of influential Republicans including Jim DeMint, Rick Santorum, and Roy Blunt.[3] This may give Akin the boost he needs to win.

* Massachusetts

Republican Scott Brown is the incumbent, and will face Democrat Elizabeth Warren, who served as Assistant to the President and Special Advisor to the Secretary of the Treasury for the Consumer Financial Protection Bureau under President Barack Obama. Polling has this race in a tie. In a televised debate, Brown was asked if he would support Mitch McConnell for re-election as Senate leader, and Brown said that he was his own man and would not commit to supporting him. Brown said,

"I already let it be very clearly known to Mitch McConnell that I'm completely disgusted as to what's going on down there. He has a lot of work to do to earn my vote because I don't work for him or Harry Reid. That's the beauty of being independent."[4]

The most recent Rasmussen poll from October 25 gives Warren a lead of 52% to 47%,

Democrat Jim Webb is retiring. Democrat Tim Kaine will face Republican George Allen. Both candidates have previously served as Virginia governors and Allen served in the Senate until he was defeated by Webb. Polling has this race tied and may come down to which presidential candidate carries Virginia in November.

* Wisconsin

Democrat Herb Kohl is retiring. Democratic Congresswoman Tammy Baldwin will face Republican former Governor Tommy Thompson. The latest Rasmussen poll from September 17 has Baldwin up by 3 points, 49% to 46%.

Independent Bernie Sanders who caucuses with the Democrats is the incumbent. John MacGovern [R] is the Republican challenger.

Likely Independent

* Maine

Republican Olympia Snowe is retiring. Democrat Cynthia Dill and Republican Charlie Summers will face Independent former Gov. Angus King. Polling predicts King will be the victor. King's positions are viewed as generally liberal leaning, and he is being treated as the de facto Democrat by the Republican campaign. It is unclear with which party he would caucus, however.